'Fast' in the Bible

“Stand fast now in your spellsAnd in your many sorceriesWith which you have labored from your youth;Perhaps you will be able to profit,Perhaps you may cause trembling.

For thus says the Lord,“To the eunuchs who keep My sabbaths,And choose what pleases Me,And hold fast My covenant,

“Also the foreigners who join themselves to the Lord,To minister to Him, and to love the name of the Lord,To be His servants, every one who keeps from profaning the sabbathAnd holds fast My covenant;

‘Why have we fasted and You do not see?Why have we humbled ourselves and You do not notice?’Behold, on the day of your fast you find your desire,And drive hard all your workers.

“Behold, you fast for contention and strife and to strike with a wicked fist.You do not fast like you do today to make your voice heard on high.

“Is it a fast like this which I choose, a day for a man to humble himself?Is it for bowing one’s head like a reedAnd for spreading out sackcloth and ashes as a bed?Will you call this a fast, even an acceptable day to the Lord?

“Is this not the fast which I choose,To loosen the bonds of wickedness,To undo the bands of the yoke,And to let the oppressed go freeAnd break every yoke?